External Sewing Unit With Pressing Member Feedback for Seam Quality
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Solution Overview
Problem
Existing sewing machines face challenges in improving the quality of seams, particularly when sewing buttonholes, due to the limitations in the frame movement and power conversion mechanisms.
Innovation Solution
A sewing machine external unit equipped with a holder, driver, pressing member, position detector, signal output part, and controller, which work together to synchronize the movement of the sewing needle and holder, ensuring precise control over the fabric positioning and needle movement based on fabric thickness and seam pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a frame with ratchet mechanism is used to convert needle movement into frame driving force, then buttonhole sewing capability is achieved, but the quality of seams deteriorates due to interference between pressing member and holder
Solution Approach 1:
The holder is designed to be movable rather than fixed, allowing it to adapt its position dynamically during the sewing process. The controller adjusts the holder's position based on the pressing member's position, preventing interference while maintaining buttonhole sewing capability. This dynamic adjustment resolves the contradiction between achieving complex stitch patterns and maintaining seam quality.
Solution Approach 2:
A position detector detects the position of the pressing member, and this information is fed back to the controller, which then adjusts the holder's position accordingly. This feedback mechanism ensures that the holder and pressing member do not interfere with each other, thereby maintaining high seam quality while enabling buttonhole sewing functionality.
2Device complexity
If the holder position is fixed during sewing, then the structure is simple, but the quality of seams deteriorates due to inability to prevent interference with pressing member
Solution Approach 1:
The holder transitions from a fixed structure to a movable one, positioned and controlled by the driver system. This dynamic positioning capability allows the holder to avoid interference with the pressing member during needle movement, thereby improving seam quality without requiring complex mechanical interference prevention mechanisms.
Solution Approach 2:
The driver acts as an intermediary mechanism between the control system and the holder, enabling precise positional control of the holder. This intermediary system allows the holder to be positioned accurately to prevent interference with the pressing member, maintaining seam quality while keeping the overall control architecture manageable.
3Manufacturing precision
If the pressing member moves with the needle, then fabric positioning precision is improved, but interference with the holder occurs during buttonhole sewing
Solution Approach 1:
The position detector continuously monitors the pressing member's position, and the controller uses this feedback information to adjust the holder's position in real-time. This coordinated control based on feedback prevents interference between the holder and pressing member while maintaining the fabric positioning precision benefits of the moving pressing member.
Solution Approach 2:
The controller serves as an intermediary that coordinates the movements of both the holder and pressing member. By processing position information and generating appropriate control signals, the controller ensures that the holder and pressing member move in a coordinated manner, preventing interference while maintaining precise fabric positioning.
Data Source
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AI summary
A sewing machine external unit (10) includes: a holder (11) holding fabric; a driver (12) being detachable from a bed of a sewing machine (1) and driving the holder along an upper surface of the bed; a pressing member (33) moving in an up-down direction according to movement of a sewing needle in the up-down direction, pressing the fabric while the sewing needle is stuck in the fabric, and rising together with the sewing needle when the sewing needle comes out of the fabric and rises; a position detector (13) detecting a position of the pressing member in the up-down direction; a signal output part (15) outputting a signal to the sewing machine; and a controller (16) outputting a needle drive signal for driving the sewing needle, and controlling driving of the holder and/or the sewing needle based on a detection result of the position detector.